Vampire Hunter D (Japanese: 吸血鬼（バンパイア）ハンターD, Hepburn: Banpaia Hantā Dī) is a series of novels written by Japanese author Hideyuki Kikuchi and illustrated by Yoshitaka Amano since 1983.

As of January 2025, 57 novels have been published in the main series, with some novels comprising as many as four volumes. They have sold over 17 million copies worldwide, making Vampire Hunter D one of the best-selling book series in history. The series has also spawned anime, audio drama, manga, comic adaptations, a video game, as well as a short story collection, art books, and a supplemental guide book.

Vampire hunter D wanders through a far-future post-nuclear war Earth that combines elements of pulp genres: western, science fiction, horror and Lovecraftian horror, dark fantasy, folklore, and occult science. The planet, once terrified by the elegant but cruel vampires known as Nobles (貴族, Kizoku), ancient demons, mutants, and their technological creations, is now slowly returning to a semblance of order and human control—thanks in part to the decadence that brought about the downfall of the vampire race, to the continued stubbornness of frontier dwellers, and to the rise of a caste of independent hunters-for-hire who eliminate supernatural threats.

Some time in 1999, a nuclear war occurred. The Nobility were vampires that planned for a possible nuclear war and sequestered all that was needed to rebuild civilization in their shelters. They use their science combined with magic to restore the world in their image. Nearly all magical creatures on Earth are genetically engineered by the Nobility to possess seemingly supernatural abilities, regeneration, and biological immortality, with a very small number being demons, gods, aliens, and extradimensional beings who survived the holocaust. Despite their technology being advanced enough to create a blood substitute as food, they still prefer to feed on humans. As such, they created a civilization where vampires and humans coexisted, eventually developing the planet into parklands and cities. The society eventually stagnates when vampire technology perfects scientific prophecy, which determines they are at their zenith of existence and doomed to fall, overthrown by humans. The human race was transformed at this time, with fear for the vampires being woven into their genetics, and the inability to remember vampire weaknesses such as garlic and crucifixes.

Unlike vampires from traditional lore, the Nobility can reproduce sexually, although their offspring will permanently cease aging after reaching physical maturity, having inherited their vampire parent's immortality.

D is a dhampir, the half-breed child of a vampire father and human mother (actually genetically engineered by the ruler and first of vampires called Sacred Ancestor using his own DNA and that of humans in an experiment to create a vampire without vampires' typical weaknesses like the sun and having to drink blood), the ideal vampire hunter. He is renowned for his consummate skill and unearthly grace but feared and despised for his mixed lineage: born of both races but belonging to neither. Often underestimated by his opponents, D possesses surprising power and resourcefulness, having most of the strengths of the Nobility and only mild levels of their common weaknesses. It has been seen in both movies that his power is not only physical, but extends into the magical realm as well. His supernatural powers make him one of the strongest beings in the world: possibly the second strongest (after only his father). However, D prefers using his physical abilities, only using his magic in times of great need. Unlike most dhampirs, D is able to live as a "normal" human; however, he is marked by his unearthly beauty and exceptionally potent aura and thus rarely accepted by human settlements. In terms of weaknesses, he is randomly susceptible to sun-sickness, a severe type of sunstroke, about once every five years (far less than most dhampirs). D also recovers from it at a rate far greater than other dhampirs. Usually, it takes several days to recover from sunlight syndrome, longer if the dhampir is exceedingly powerful, but D recovered in a few hours (around 1–6 hours) despite being one of the strongest dhampirs alive. Otherwise, D does not appear to suffer from other vampiric weaknesses usual to dhampirs, being able to physically restrain opponents with his aura and having godlike reflexes surpassing even those of Nobles.

His symbiotic left hand states, in Vampire Hunter D: Bloodlust: "The Herarchy of us became impatient with the heartless David and impaled The Lord on 'The Sword'". Speculation on whether "The Sword" is D's sword or not is debatable. Here, however, the movie differs sharply from the book from which it takes its story, Vampire Hunter D: Demon Deathchase, and future entries in the novel series do not differentiate between Dracula, The Vampire King, The Sacred Ancestor and D's father, proposing that they are one and the same.

D rides a cybernetic horse with mechanical legs and other enhancements, wields a crescent longsword which looks similar to Yoshitaka Amano's scimitar sword design found in many of his works of art, but the sword has a hefty length, similar to that of a Japanese nodachi. D always wears a mystical blue pendant; it prevents many of the automatic defenses (such as laser fields and small nuclear blasters) created by the Nobility in past millennia from working properly and allows him to enter their sealed castles. He also uses wooden needles in the novels and game, which he can throw with super speed. He protects his milk-white face from the noonday sun with long black hair, flowing black clothing and cape, and the shadow of a wide-brimmed hat. D appears to be a youth, 17 or 18 years old, though D's age is unknown (the novels reveal that he is more than 10,000 years old). His beauty is mesmerizing, often unintentionally wooing women and sometimes flustering men.